"""
three_d =[
    [
        [1,2],
        [3,4]
    ],
    [
        [5,6],
        [7,8]
    ]
]
"""

three_d = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]]
flattern = [
    three_row
    for onw_row in three_d
    for second_row in onw_row
    for three_row in second_row
]
print(flattern)
